The Motherisk Alcohol and Substance Use Helpline at The Hospital for Sick Children in Toronto, Canada, is a unique telephone service providing evidence-based information on the negative effects associated with alcohol and substance use in pregnancy and lactation. We describe the characteristics of the service, the demographics of the callers, and the inquiries made during its first ten years of service. Since its inception in November 1998 until November 2008, almost 20,000 calls had been received with 60% of calls initiated by pregnant and breastfeeding women, the remainder from various health care providers. Most women exposed to alcohol and substances were of Caucasian descent (80%), employed (65%), and married (46%) with some level of post-secondary education (52%). The demographics of the callers deviate from the well-documented cohort of women at risk of engaging in alcohol and substance use in pregnancy and lactation, confirming that a selective group of women is more likely to use the services offered by the Motherisk program. Thus, further efforts are required to reach out to the subgroup of women at high risk of continuing their harmful behaviors during pregnancy and lactation.